1. Field
Certain aspects of the present disclosure generally relate to wireless communication and, more particularly, to a technique for notification of emergency warnings over cellular networks.
2. Background
Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE) systems, and orthogonal frequency division multiple access (OFDMA) systems.
Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link may be established via a single-in-single-out, multiple-in-single-out or a multiple-in-multiple-out (MIMO) system.
In some wireless standards such as LTE, an Earthquake and Tsunami Warning System (ETWS) is developed. In LTE standard, the warning notification is delivered over the system information broadcast message. However, the normal system information block (SIB) transmission and its modifications are restricted by a ‘modification period.’ For urgent emergency warning messages, the system should not waste any time and the modification period may be too long depending on the nature of the emergency situation.
Therefore, there is a need in the art for an emergency warning scheme that is not restricted by a modification period. The emergency information should be transmitted to all the user equipments as soon as the emergency situation happens.